Polymers (referred to as polydiacetylenes) obtained by solid-state polymerization of 1,4-di-substituted diacetylene monomers (R—C≡C—C≡C—R′: wherein, R and R′ represent identical or different monovalent organic substituents) have a main chain structure consisting of a repeating unit in the form of ═CR—C≡C—CR′═, and form macromolecules having a molecular weight on the order of several million.
Although polydiacetylenes are characterized by the main chain having a fully conjugated, extended chain structure, they have also attracted much attention from the view point of optically active materials, such as an extremely large third order non-linear optical susceptibility [X(3)=10−9 to 10−10 esu, C. Sauteret et al., Phys. Rev. Lett., 36, 956 (1976)], and photo-induced-phase transition phenomena [S. Koshihara et al., J. Chem. Phys., 92, 7581 (1990)] based on excitons of the conjugated n-electron system of the main chain.
However, the majority of common polydiacetylenes are insoluble in solvent due to the rigidity of the main chains, and since they also decompose without melting when heated, it has been essentially impossible to measure their molecular weight, molecular weight distribution and other solution properties.
In contrast, in the case of 1,4-di-substituted diacetylene polymers containing such long side chains as flexible and easily solvated substituents in the form of R and R′ in the aforementioned repeating unit (for example, in the case in which R and R′ represent (CH2)4OCONHCH2COOC2H5), molecular weight, molecular weight distribution and other solution properties can be measured on an exceptional case due to being soluble in polar solvents.
However, there has of yet been no research nor development conducted with an intention to control the average degree of polymerization, and the molecular weight distribution even for those soluble polydiacetylenes, thus no sample of 1,4-di-substituted diacetylene polymers based on said control is near at hand.
One of the technical background factors behind these circumstances is as follows. In the case of polyaddition reactions of common olefin monomers, molecular weight of polymers can be controlled by the amount of the initiator against the monomer, and such a control is also possible for polycondensation reaction of polyesters, polyamides and so forth by changing the relative ratio of the reactants.
In contrast, polymerization of diacetylene compounds is quite unique in the sense that polymerization initiates without any common initiators, but by the external stimulation such as high energy beams, UV-light, shear stress, thermal treatment and so forth.
The cause of this difficulty in controlling molecular weight and molecular weight distribution is that, in the case of solid phase polymerization of diacetylene compounds, in addition to being unable to specify the concentration of the active sites of polymerization, since no initiator is added on purpose. In addition, propagation proceeds very rapidly via chain reaction, high molecular weight polymers are present in the unreacted monomer phase in the solid solution state even in the very early stages of the reaction, thereby making it impossible to isolate low molecular weight oligomers in a good yield.
This is also the case even for polydiacetylenes having molecular weights ranging from ten thousand to several million.
Incidentally, although the relationship between polymer conversion rate of diacetylene compound [substituent R═R′═(CH2)4OSO2C6H4CH3] and molecular weight has been described (G. Wenz et al., Mol. Cryst. Liq. Cryst. 96, 99 (1983)), as shown in FIG. 1, in the state of a conversion rate of 0.2%, namely when 99.8% of the monomer still remains, the molecular weight of the formed polymer is already within the range of 10,000 to 100,000, and at a conversion rate of 4.5%, the molecular weight covers a continuous, wide distribution from several ten thousands to several million.
Moreover, at a conversion rate of 42% or higher, the product consists primarily of only polymers having high molecular weights ranging from several hundred thousands to several million.
On the basis of such experimental results, the selective and efficient preparation of diacetylene polymers in which molecular weight and molecular weight distribution are controlled has been judged to be extremely difficult during the course of the polymerization reaction with respect to polydiacetylenes.
On the other hand, in the aspect of practical use, materials made from polydiacetylenes have been evaluated as being conjugated polymers having extremely large third order non-linear optical susceptibility as well as other superior characteristics.
However, since polydiacetylenes happen to cause light scattering due to the phase separation in a matrix material based on the rigidity of the main chains, improvement of their processability has been desired.
In consideration of the circumstances surrounding polydiacetylenes as described above, the object of the present invention is to provide a production process of 1,4-di-substituted diacetylene polymers by controlling the average degree of polymerization and molecular weight distribution within predetermined ranges, 1,4-diacetylene polymers according to said production processes, useful compositions based on the 1,4-di-disubstituted diacetylene polymers, and constitutions of a member that uses said compositions.